NEBU

The nebulin-like motif or nebulin repeat is a tandemly repeated actin-binding module of about 35 amino acids. The repeat is named after the nebulin protein, which is a large protein specific for vertebrate skeletal muscle that may regulate the length of thin filaments. Nebulin contains about 185 copies of the repeat and those in the central part of nebulin are organised into seven-module super-repeats, which seems to reflect an interaction with tropomysin/troponin [(PUBMED:8168478)]. Nebulin repeats occur in metazoan actin-binding proteins, most of which are specific for muscle tissues. Most nebulin repeat proteins contain a C-terminal SH3 domain and/or a N-terminal LIM zinc-binding domain. The repeats in nebulin and nebulette bind filamentous actin (F-actin) and may also associate with tropomyosin and troponin. The nebulin repeat has a predicted alpha-helical secondary structure and contains a central conserved SXXXY motif [(PUBMED:8168478), (PUBMED:9733644), (PUBMED:12446728)].